A cross-linked curing compound, 1-methyl-2-vinyl-4,6-heptadienol, of the formula: ##STR1## has been disclosed in the "Tetrahedron Letters," No. 43 pages 3813-3816 (1970, United Kingdom). This compound is obtained by the reaction of butadiene with an aldehyde in the presence of a palladium complex catalyst. Since this compound has a conjugated double bond and a vinyl substituent, it is highly reactive. Therefore, cross-linking occurs in the presence of a catalyst such as a metal salt of naphthenic acid, an organic peroxide or azobis-isobutylonitrile or a curing reaction under heating. Thus, it is claimed to be useful as a reactive diluent for oil-based paints or air-drying alkyd-resin paints. However, we have demonstrated experimentally that this compound, when used as a diluent for an alkyd-resin paint, exhibits volatility so high as to degrade the workability of the paint.